Inhaler for multiple use

ABSTRACT

A multiple dose inhaler for the inhalation of a dry powder medicament is provided. The inhaler includes (a) a housing defining an inlet, an outlet spaced from the inlet, and an airflow path from the inlet to the outlet; (b) an elongate carrier disposed within the housing, a first portion of which carries discrete doses of the medicament, the doses being spaced from one another at predetermined substantially equidistant intervals along the length of the elongate carrier; (c) a dispensing wheel upon which the first portion of the carrier is wound; (d) a take-up wheel constructed to incrementally receive the elongate carrier from the dispensing wheel as it is unwound therefrom during use; (e) an advancement mechanism constructed to incrementally advance the elongate carrier within the housing from the dispensing wheel to the take-up wheel when the inhaler is actuated for use; (f) a brake constructed to releasably resist further advancement of the elongate carrier by the advancement mechanism after the elongate carrier has advanced an incremental distance substantially equal to the predetermined distance between the discrete doses; and (g) a trigger constructed to engage and release the brake, allowing further advancement of the elongate carrier.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an inhaler for multiple use for amedicament in powdered form to be used in conjunction with an elongatecarrier carrying discrete doses of said medicament, said elongatedcarrier comprising a carrier body and a peelable cover strip coveringand enclosing said discrete doses, said inhaler comprising a housing, anair inlet, a powder dispensing station and an air outlet, said inlet,said outlet and said dispensing station being interconnected by an airconduit for inhaling, said inhaler further comprising displacing meansfor moving said elongate carrier so as to successively locate a discretedose in said dispensing station and means for separating said peelablecover strip from said carrier body in connection with said dispensingstation.

BACKGROUND TO THE INVENTION

An inhaler of the above general kind has several advantages incomparison to standard multiple powder inhalers containing a largenumber of doses in a store for the powdered drug from which the powderis fed to a dispensing station.

The drug thus can be protected against moisture in a simple andefficient way since each individual dose of the drug can be tightlyenclosed and sealed between the cover strip and the elongate carrier.The utilization of the drug is high since there is no store that mayhave to be overfilled to ensure definitely that there is drug availableas long as the dose counter indicates there should be. The number ofdoses can be varied in a simple way by cutting different lengths from acontinuous elongate carrier. It is easy to arrange a simple countingdevice indicating the number of doses used or remaining. A simpleindication that all doses have been used up may be obtained merely bythe fact that the carrier is used up, which is easy to determine. Thedevice may finally also be designed to be reusable several times whichwould make the device cheap in use, since it is easy for the patient torefill the device in a safe way without any risk of exposing the drug tomoisture.

A further advantage of using an elongate carrier is that the countingdevice may be dispensed with entirely if each dose is numbered, i.e. anumeral is assigned to each dose, the numerals being consecutivelyvisible through an opening in the housing. Preferably the doses arenumbered backwards with the highest numeral assigned to the first dose.In this way a simple way of indicating the number of doses remaining maybe obtained without any need for a counting mechanism.

An inhaler of the kind as described in the introduction above and in thepreamble of the main claim is for instance disclosed in GB-A-2 242 134.This prior art device utilizes the depressions or cavities in anelongated carrier in cooperation with indexing or registering means inorder to control that the depressions containing the doses arepositioned correctly in the dispensing station. In one embodiment thedevice is provided with a spool taking up the cover strip (the indexingmeans are here engaging the depressions which are used to move thecarrier). However, since the diameter of the spool taking up the coverstrip will vary in dependence of the amount of strip wound on the spool,the winding speed of the cover strip consequently also will vary,whereas the movement of the carrier will not. To compensate for this,the spool taking up the cover strip has been provided with a rathercomplicated friction coupling allowing the take-up spool to slip inrelation to the movement of the elongated carrier.

In an alternative embodiment which is suggested, but not described indetail, the distances between the depressions in the elongate carrierhave been varied in order to compensate for the above effect, whichhowever complicates the manufacturing and filling process for theelongate carrier. Further, the number of doses generally cannot easilybe varied by cutting a long prefabricated carrier part into pieceshaving different lengths.

In both cases the elongate carrier (and the depressions in particular)must be comparatively stiff to permit the use of the depressions asactuating means in conjunction with indexing or registering means. Thismay be undesirable in some applications. The use of the depressions incombination with the indexing means also results in limitations on thesize of the depressions since the depressions, apart from the stiffnessmentioned above, also have to have a minimum size in order not to slipthrough the indexing or registering means. This means that the dosesalso have to have a minimum size.

Some other related prior art devices are disclosed in for instance WO90/13327, WO 90/13328, and EP-A1-0 469 814.

BRIEF DESCRIPTION OF THE INVENTIVE CONCEPT

The object of the invention is to obtain an inhaler of the kinddescribed introductorily which also allows the use of carriers havingsmall cavities or depressions containing small doses of highly potentdrugs and which, if necessary, may be made of a material which issufficiently flexible to be deformed to some extent in the dispensingstation in order to facilitate the ejection of the powdered drug fromthe depression before or during inhalation. A further object of theinvention is to provide an inhaler for multiple doses which has a simpleconstruction and which is cheap to produce.

In one aspect, the invention features a multiple dose inhaler for amedicament in powdered form. The inhaler includes: (a) a housingdefining an inlet, an outlet spaced from the inlet, and an airflow pathfrom the inlet to the outlet; (b) an elongate carrier disposed withinthe housing, a first portion of which carries discrete doses of themedicament, the doses being spaced from one another at predeterminedsubstantially equidistant intervals along the length Of the elongatecarrier; (c) a dispensing wheel upon which the first portion of theelongated carrier is wound; (d) a take-up wheel constructed toincrementally receive the elongate carrier from the dispensing wheel asit is unwound therefrom during use; (e) an advancement mechanismconstructed to incrementally advance the elongate carrier within thehousing from the dispensing wheel to the take-up wheel when the inhaleris actuated for use; (f) a brake constructed to releasably resistfurther advancement of the elongate carrier by the advancement mechanismafter the elongate carrier has advanced an incremental distancesubstantially equal to the predetermined distance between the discretedoses; and (g) a trigger constructed to engage and release the brake,allowing further advancement of the elongate carrier.

SHORT DESCRIPTION OF THE APPENDED DRAWINGS

FIG. 1 is a schematic drawing of a preferred embodiment showing thebasic principles of the inhaler,

FIGS. 2-5 are schematic drawings that show the ratchet and pawl/camfollower advancement mechanism shown in FIG. 1 in a sequence ofpositions, starting at a first position, in which the pawl is engagedand the cam follower is not (FIG. 2), changing position in FIGS. 3 and4, and returning to the starting position in FIG. 5.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

It should be noted that all terms used below relating to the exactorientation in the appended drawings, such as "upper", "lower","clockwise" etc only relate to the drawings as such and are not to beconstrued as limiting the scope of the invention.

As can be seen in FIG. 1, the inhaler in a preferred embodimentcomprises a housing 1 with a mouth-piece 9. An air inlet 6 is connectedto an air outlet 8 via a dispensing station 7 by means of an air conduit37. An elongated carrier 2 carrying the doses of the drug comprises alower tape 3 provided with depressions or cavities 5 containing the drugand a continuous peelable cover strip 4 sealing the cavities. Thepeelable strip 4 is separated from the lower tape 3 at the dispensingstation 7, thus exposing the drug in any cavity located in thedispensing station. The dispensing station 7 is formed as a constrictionin the air conduit 37, the lower tape 3 forming one of the walls of theconstriction. When the inhaler is actuated for use, a cavity 5 islocated centrally in the dispensing station 7.

The cover strip 4 is guided away from the lower tape 3 by means of aguide roller 18 located just before the dispensing station 7 and iswound onto a first take-up spool 15 fixedly attached to an actuatingwheel 12 partly extending outside the housing 1. The spool 15 and theactuating wheel are rotatably supported on a common axis 17 supported inthe housing 1. The periphery of the actuating wheel 12 is provided withteeth 13, which may serve a double function, namely to enhance the gripwhen the wheel is actuated manually (in an embodiment in which theperiphey of the wheel extends outside the housing) and to cooperate witha double pawl 22 in a manner to be described more in detail below inconnection with FIGS. 2-5.

The lower tape 3 is guided onto a second take-up spool 11 by means of asecond guide roller 19 located after the dispensing station 7. Thesecond take-up spool 11 is driven by the first take-up spool 15 by meansof a belt 36 which for instance may be made of rubber. This belt willserve as a cheap and simple friction coupling compensating for anydifferences in the respective winding speeds of the lower tape 3 and thecover strip 4. Normally there should not be any great differences in thewinding speeds provided that the thickness of the lower tape and thethickness of the cover strip are more or less equal and that the twotake-up spools have the same diameter and provided that any influencefrom the cavities in the carrier can be disregarded.

The two guide rollers 18, 19 also serve to orient and align the lowertape 3 correctly in the dispensing station 7. Since the dispensingstation 7 is designed as a constriction in the air conduit 37, the airrespired through the air conduit will move rapidly and turbulentlyacross the mouth of the cavity in the lower tape, thus lifting the doseof powdered drug out from the cavity.

The airstream will move the powdered dose up along the air conduit 37 tothe mouth-piece 9. The air conduit 37 and/or the mouth-piece 9 isprovided with deaggregation means 38 to break up any aggregates thatcould have been created in the powder formed dose. Upon impaction themedicament with powder aggregates will break up into a finely dividedmedicament having a high amount of particles having a size within therespiratory range, that is smaller than 10 μm, preferably smaller than 5μm.

The construction form and size of the deaggregation means can be variedbut preferably they can have a form of deflector devices as described inEP-B-237 507, or comprise planar impaction surfaces as described in WO92/04069 or any other suitable form which provides a deaggregatingeffect. The deaggregation means could be provided in the air conduit 37and/or in the mouthpiece 9 as shown in FIG. 1.

If a fresh tape is to be mounted in the inhaler, the free end of thecover strip 4 is firmly attached to the take-up spool 15 and the freeend of the lower tape 3 is attached to the take-up spool 11.

The carrier 2 is stored on and unwound from a third spool 10 which maybe replaceable.

The carrier 2 further is provided with equidistant perforations (notshown) which preferably are located along the longitudinal edges of thecarrier. These perforations are intended to engage sprockets 21 on asprocket wheel 20 which is rotatably journaled in the housing 1 suchthat the sprocket wheel 20 rotates with the carrier 2 when the carrier 2is displaced longitudinally. A ratchet wheel 23 provided with recesses25 and a cog wheel 24 provided with recesses 26 further are attachedcoaxially and rigidly with the sprocket wheel 20 so as to co-rotatetherewith. The cog wheel 24 serves to actuate a counting device in theshape of a cog wheel 16 provided with a scale visible through anaperture in the housing (not shown) and serves additionally as a cam fora purpose which will be described more in detail below.

FIGS. 2-5 illustrate the functional details of the indexing means andparticularly some details not shown in FIG. 1.

These drawings thus show the carrier 2 with the lower tape 3, thedepressions 5 and the cover strip 4, the sprocket wheel 20 with thesprockets 21, the ratchet wheel 23, the cog wheel 24, the guide roller18, the double pawl 22, the actuating wheel 12 with the teeth 13 and thetake-up spool 15, and the trigger 14.

The drawings further show how the double pawl 22 is provided with afirst pawl 27 cooperating with the ratchet wheel 23 and a second pawl 28cooperating with the teeth 13 of the actuating wheel 12. The first andthe second pawl are fixedly attached relative to each other. The doublepawl 22 is carried swingably on an axle 30 and is provided with aeccentric shoulder 29 cooperating with the trigger 14.

The indexing means further is provided with a detent 32 cooperating witha shoulder 34 on the second pawl 28. The shoulder 34 has an upper and alower surface for engagement with the detent 32. The upper surface isoriented generally in parallel with the longitudinal extent of thedetent 32. The lower surface, however, is oriented generallyperpendicularly to the upper surface.

A cam follower 31 cooperating with the cog wheel 24 is fixedly attachedrelative to the detent 32. The detent and the follower are rotatablycarried on an axle 35. The detent and follower are spring-biased in acounter-clockwise direction whereas the double pawl is spring-biased ina clockwise direction. The trigger 14 is spring-loaded by a spring 33biasing the trigger outwardly from the housing 1.

FIG. 2 illustrates the initial position of the indexing means, before acavity containing a new dose is moved into the dispensing station. Inthis position the trigger 14 rests on the shoulder 29. The pawl 28 is inengagement with the teeth 13 by which means the actuating wheel 12 isblocked. The pawl 27 is further in engagement with the ratchet wheel 23by which means the sprocket wheel 20 is blocked. Consequently thecarrier 2 is blocked. The detent 32 finally rests upon the upper surfaceof the shoulder 34, thus keeping the cam follower out of engagement withthe cog wheel or cam 24.

When the inhaler is to be used, a cavity containing a new dose of thepowdered drug normally is moved into the dispensing station. In order tofree the wheels 12 and 20 and to allow this movement of the carrier, thetrigger 14 is depressed against the action of the spring 33 as shown inFIG. 3. The trigger acts on and displaces the shoulder 29 causing thedouble pawl 22 to swing counter-clockwise against the spring bias. Bythis means the second pawl 28 is disengaged from the teeth 13 of theactuating wheel 12 and the first pawl 27 is disengaged from the recesses25 on the ratchet wheel 23. The detent 32 slides off the upper surfaceof the shoulder 34 under the influence of the spring bias and swingsslightly counterclockwise such that its end rests against the lowersurface of the shoulder 34, thus preventing the double pawl 22 fromswinging clockwise, thereby keeping both pawls 27 and 28 disengaged fromtheir respective wheels. As a result of the above movement of the detent32, the cam follower 31 will swing into one of the recesses 26 of thecog or cam wheel 24.

It should be noted that the recesses 26 on the wheel 24 are orientedsuch relative to the recesses 25 on the ratchet wheel 23 that the camfollower 31 can swing into a recess 26 when the pawl 27 can engage arecess 25. Both the actuating wheel 12 and the sprocket wheel 20 now arefree to rotate.

FIG. 4 illustrates what happens when the actuating wheel is rotated inorder to move a new dose of the drug into the dispensing station.

Since the cover strip 4 is firmly attached to the spool 15, a rotationof the actuating wheel 12 will result in that the cover strip is woundonto the spool 15, thus pulling the carrier 2 and the lower tape 3forward through the inhaler. This forward movement is however onlypossible as long as the sprocket wheel 20 and the take-up spool 15remain free to rotate. The lower tape 3 will be wound onto the spool 11since the spool 11 is driven by the actuating wheel 12 via the spool 15and the belt 36.

The cam follower 31 will swing clockwise under the influence of theteeth on the cog wheel 24 which in this instance serve as cams. Thiswill force the detent 32 out of engagement with the lower surface of theshoulder 34 to slide on to the upper surface of the shoulder, thusfreeing the double pawl 22. When the detent 32 rests on the uppersurface of the shoulder 34, the cam follower 31 will return to itsoriginal position, out of engagement with the cog or cam wheel 24.

The double pawl 22 can however not swing back and block the respectivewheels 12 and 23 since the pawl 27 now slides upon the outer peripheryof the ratchet wheel between two adjacent recesses 25. The actuatingwheel thus can be rotated until the pawl 27 engages the next recess 25on the periphery of the ratchet wheel 23.

When the pawl 27 again engages a recess 25 on the ratchet wheel 23, thecomponent parts of the indexing means have returned to its originalstate before the actuation of the trigger, as can be seen in FIG. 5.

The angular distance between the recesses 25 is chosen such that thisrotation of the ratchet wheel 23 corresponds to an angular movement ofthe sprocket wheel 20 corresponding exactly to the distance between twoadjacent depressions or cavities. In this way it is ensured that acavity containing a fresh, exposed dose of the powdered drug replacesthe cavity previously being located in the dispensing station,irrespective of whether the dose contained in that cavity has been usedor not (if a dose has been left exposed in the dispensing station forsome time, a new dose preferably should be used), and the inhaler isready for inhalation.

A clear indication that all doses of drug are used up and that theinhaler is empty is obtained by the fact that the actuating wheel willrotate freely as soon as the end of the carrier 2 has left the sprocketwheel 20. This is due to the fact that the sprocket wheel 20 togetherwith the ratchet wheel 23 will not rotate with the actuating wheel whenthe carrier has left the sprocket wheel. This results in that theindexing means will remain in the state shown in FIG. 3 after thedepression of the trigger 14, in which state the actuating wheel isfreely rotatable, since the cam follower 35 will not disengage thedetent 32 from the lower surface of the shoulder 34 and the pawl 28 willremain disengaged from the actuating wheel.

Since the cover strip 4 is used to pull the carrier 2 through theinhaler and the lower tape 3 serves no other purpose than to formsealable containers or cavities for each individual dose of the drug,the design of, the dimensions of and the choice of materials in thelower tape 3 and the cavities can be varied so as to optimize therelease of the powdered drug from the cavities into the air stream.

The cavities thus for instance may be designed to be relatively shallowwhich may facilitate the release of the drug. The thickness or thematerial of the tape can be chosen such that the walls, particularly thebottom in the cavities is flexible enough to allow the cavities to bedeformed or flexed as a consequence of the subpressure obtained at themouths of the cavities when the accelerated airstream in theconstriction sweeps past the mouths. This flexing may aid in breaking upthe powder in the cavities, thus facilitating the release of the powderinto the airstream. The movement of the bottom may even be strong enoughto literally eject the powder from the cavities.

It would also be possible to deform the cavities mechanically by placingthe lower tape under tension over an even surface or shoulder in thearea of the constriction, the surface pushing the bottom of the cavitiesupwardly in the dispensing station when the tape is pulled over thesurface. By these means the powder would be more or less pushed into theairstream.

POSSIBLE MODIFICATIONS OF THE INHALER

The inhaler of course can be modified in many ways within the scope ofthe attached claims.

Thus the indexing means in the embodiment illustrated comprise asprocket wheel for engagement with perforations in the tape. Thissprocket wheel is illustrated as being located before the place ofseparation of the lower tape and the cover strip. The sprocket wheel mayhowever be located after the place of separation and after thedispensing station, engaging the lower tape only or the cover striponly. This may for instance have advantages in regard of the design ofthe inhaler. However, in some embodiments the carrier might have to berelatively strong in order not to be deformed against the sprocket wheelunder the influence of the pulling action when the sprocket wheel isblocked after a forward movement of the carrier, since such deformationmay result in a incorrect positioning of a cavity in the dispensingstation. Depending on the respective materials used, it may normally bepreferable to locate the sprocket wheel before the place of separationas illustrated in the preferred embodiment, in this way utilizing thecombined strength of the lower tape and the cover strip.

In this context it should however be noted that the carrier does notrisk being deformed in the preferred embodiment illustrated above, sincethe sprocket wheel 20 and the take-up spool 15 for the cover strip 4 arelocked simultaneously at the end of an intermittent movement of thecarrier.

However, if the sprocket wheel is not locked at the end of eachintermittent movement, it may be advisable to provide a friction brakeor an equivalent thereof acting on the sprocket wheel or on the carrierbefore the dispensing station in order to counteract any forcestransmitted from the take-up spool to the elongate carrier, thuspreventing the carrier to move after the end of the intermittentmovement under the action of these forces, in order to ensure that thecavity always is located correctly in the dispensing station.

It is of course not necessary that indexing wheel, as for instance thesprocket wheel, is locked at the end of each movement of the carrier. Itwould in principle be sufficient if the indexing wheel merely activatedthe mechanism for locking the take-up spool in a distinct and securemanner.

It may also be possible to use a friction roller or wheel, which forinstance may be knurled, engaging the carrier as an indexing means. Thisroller should cooperate with a second roller also preferably having africtional surface, the carrier being held between the two rollers.Depending on the circumstances, one or both of the two rollers may belocked after a predetermined angle of rotation in order to aid inblocking the movement of the carrier when a new or fresh dose of themedicament has been introduced into the dispensing station.

The elongate carrier may also be mounted on a storage roll in anexchangeable cassette, the free end of the carrier being attached to atake up spool, also located in the cassette.

I claim:
 1. A multiple dose inhaler for a medicament in powdered formcomprising:(a) a housing defining an inlet, an outlet spaced from saidinlet, and an airflow path from said inlet to said outlet; (b) anelongate carrier disposed within said housing, a first portion of whichcarries discrete doses of the medicament, said doses being spaced fromone another at predetermined substantially equidistant intervals alongthe length of said elongate carrier; (c) a dispensing wheel upon whichsaid first portion of said elongated carrier is wound; (d) a take-upwheel constructed to incrementally receive said elongate carrier fromsaid dispensing wheel as it is unwound therefrom during use; (e) anadvancement mechanism constructed to incrementally advance said elongatecarrier within said housing from said dispensing wheel to said take-upwheel when said inhaler is actuated for use; (f) a brake constructed toreleasably resist further advancement of said elongate carrier by saidadvancement mechanism after said elongate carrier has advanced anincremental distance substantially equal to said predetermined distancebetween said discrete doses; and (g) a trigger constructed to engage andrelease said brake, allowing further advancement of said elongatecarrier.
 2. An inhaler of claim 1 wherein said brake comprises anindexing wheel constructed to engage regions of said elongated carrier,and a member constructed to engage said indexing wheel to resistrotation of said indexing wheel after a predetermined angle of rotation.3. An inhaler of claim 2 wherein said elongated carrier includes aplurality of perforations and said indexing wheel includes a pluralityof sprockets constructed to engage said perforations.
 4. An inhaler ofclaim 1 wherein said elongate carrier includes a plurality ofequidistant depressions and each of said discrete doses is contained bya said equidistant depression.
 5. An inhaler of claim 1 furthercomprising a cover sheet disposed over said elongated carrier to protectsaid discrete doses.
 6. An inhaler of claim 5 further comprising asecond take-up spool to receive said cover sheet as it is removed fromsaid elongated carrier to allow delivery of said discrete doses.
 7. Aninhaler of claim 6 wherein said second take-up spool is driven, causingsaid cover sheet to be peeled from said elongated carrier by therotation of said second take-up spool.
 8. An inhaler of claim 7 whereinsaid advancement mechanism comprises an actuating wheel constructed todrive said take-up spool for said elongated carrier, and said secondtake-up spool is mounted rigidly and coaxially on said actuating wheelfor rotation therewith.
 9. An inhaler of claim 1 further comprising amouth-piece mounted at said air outlet, said mouth-piece defining anopening through which said doses can be inhaled during use.
 10. Aninhaler of claim 1 further comprising a deaggregation portion providedin said airflow path.
 11. An inhaler of claim 10 further comprising adeaggregation portion provided in said mouthpiece.
 12. A multiple doseinhaler for a medicament in powdered form comprising:(a) a housingdefining an inlet, an outlet spaced from said inlet, and an airflow pathfrom said inlet to said outlet; and, within said housing, (b) anelongate carrier, a first portion of which carries discrete doses of themedicament, said doses being spaced from one another at predeterminedsubstantially equidistant intervals along the length of said elongatecarrier; (c) a dispensing wheel upon which said first portion of saidelongated carrier is wound; (d) a take-up wheel constructed toincrementally receive said elongate carrier from said dispensing wheelas it is unwound therefrom during use; (e) an advancement mechanismconstructed to incrementally advance said elongate carrier within saidhousing from said dispensing wheel to said take-up wheel when saidinhaler is actuated for use, said advancement mechanism comprising aratcheted wheel having a plurality of teeth; (f) a brake constructed toreleasably resist further advancement of said elongate carrier by saidadvancement mechanism after said elongate carrier has advanced anincremental distance substantially equal to said predetermined distancebetween said discrete doses, said brake comprising a first pawlrotatably mounted for movement between a first position in which saidfirst pawl engages said teeth of said ratcheted wheel and a secondposition in which said first pawl is free of said teeth; and (g) atrigger constructed to release said brake by engaging said first pawland rotating it to said second position, allowing further advancement ofsaid elongate carrier.
 13. An inhaler of claim 12 wherein said take-upwheel is driven by said actuating wheel.
 14. An inhaler of claim 13wherein said brake further comprises a sprocket wheel constructed toengage said elongated carrier as said elongated carrier is advancedbetween said dispensing wheel and said take-up wheel.
 15. An inhaler ofclaim 14 wherein said brake further comprises an inner cog wheel and anouter ratchet wheel, mounted rigidly and coaxially on said sprocketwheel, a second pawl constructed to rotate with said first pawl betweena first position in which said second pawl engages said outer ratchetwheel and a second position in which it is disengaged therefrom, saidsecond pawl being in said first and second positions when said firstpawl is in said first and second positions, respectively.
 16. An inhalerof claim 15 wherein said cog wheel is constructed to drive a countingdisc carrying a consecutive series of indicia, and an opening in saidhousing through which at least one of said indicia can be viewed,causing said counting disc to be intermittently rotated synchronouslywith each intermittent movement of said elongated carrier.
 17. Aninhaler of claim 15 wherein said first and second pawls are biasedtoward their respective first positions.
 18. An inhaler of claim 17wherein said brake further comprises a cam follower rotatably mountedfor movement between a first position in which a first portion of saidcam follower engages a first surface of said first pawl when said firstpawl is in its second position, preventing movement of said first pawltoward its first position, and a second position in which said firstportion of said cam follower engages a second surface of said firstpawl, preventing rotation of said cam follower.
 19. An inhaler of claim18 wherein said cam follower is biased towards its first position. 20.An inhaler of claim 19 wherein said cam follower further comprises asecond portion constructed to engage said ratchet wheel when said camfollower is in its first position and to slide out of engagement andover a peripheral surface of said ratchet wheel when said cam followeris rotated towards its second position.
 21. An inhaler of claim 14wherein said elongated carrier includes a plurality of perforations andsaid sprocket wheel includes a plurality of sprockets positioned forengagement with said perforations.
 22. An inhaler of claim 12 whereinsaid elongate carrier includes a plurality of equidistant depressionsand each of said discrete doses is contained by a said equidistantdepression.
 23. An inhaler of claim 12 further comprising a cover sheetdisposed over said elongated carrier to protect said discrete doses. 24.A method of delivering a finely divided powdered medicament to a humancomprising the steps of:(a) providing an inhaler comprising:(i) ahousing defining an inlet, an outlet spaced from said inlet, and anairflow path from said inlet to said outlet; (ii) an elongate carrierdisposed within said housing, a first portion of which carries discretedoses of the medicament, said doses being spaced from one another atpredetermined substantially equidistant intervals along the length ofsaid elongate carrier; (iii) a dispensing wheel upon which said firstportion of said elongated carrier is wound; (iv) a take-up wheelconstructed to incrementally receive said elongate carrier from saiddispensing wheel as it is unwound therefrom during use; (v) anadvancement mechanism constructed to incrementally advance said elongatecarrier within said housing from said dispensing wheel to said take-upwheel when said inhaler is actuated for use; (vi) a brake constructed toreleasably resist further advancement of said elongate carrier by saidadvancement mechanism after said elongate carrier has advanced anincremental distance substantially equal to said predetermined distancebetween said discrete doses; and (vii) a trigger constructed to engageand release said brake, allowing further advancement of said elongatecarrier; (b) causing the human to actuate said advancement mechanism tomove a said dose into said airflow path; and (c) causing the human toinhale through said outlet to receive said dose through said outlet.